1. Field of the Invention
The present invention relates to hangers for supporting objects on a wall, and more particularly to single-piece hangers which penetrate thin or hollow walls, such as, wallboard or wood paneling, and when fully inserted, lock in place against rotation within, or removal from, its mounting hole.
2. Prior Art
In the past, secure attachment of wall-penetrating hangers to wallboard, or plaster walls, has been made difficult by the nature of the wall materials and the weight and movements to which the hangers are subjected. For example, wallboard (also known as sheet rock or dry wall) typically comprises a relatively thick layer of gypsum sandwiched between paper layers, and exhibits relatively soft composition, while plaster walls generally comprise substantially homogeneous construction, but suffer from a tendency to crumble or otherwise break down, when penetrated. Wood paneling is about 1/8 to 1/4 inch thick and can be plywood, masonite or compressed wood particles having a decorative face such as a wood grain face.
Most wall-penetrating hangers known in the prior art today display characteristics which are undesirable and render such hangers practically inoperable after a short period of time in use.
For example, wall-penetrating hangers of the kind typified by the patents to Jones U.S. Pat. No. 241,991 and Wagner U.S. Pat. No. 1,445,372 are wire-type hangers which are inserted through pre-drilled holes, and have portions with ends that pass through, and are positioned behind the wall. The ends abut and bear against the rear surface of the wall when weight is applied to the hook at the front of the wall. However, because of the repeated applications of weight to the hook, eventually the hole enlarges and the hanger works loose in its hole. Thus, the capacity of the hanger to anchor itself in the wall is substantially reduced and its weight-supporting function minimized. Wall-penetrating hangers of the kind exemplified by the patents to Smith U.S. Pat. No. 3,219,302 and Jones U.S. Pat. No. 2,789,783 employ penetrating or cutting tips on the free ends of the tail portion of each hanger.
In the Wagner patent, a single piece of wire, folded upon itself, is bent into an L-shaped body having a pair of legs normally tending to spread apart. Each leg has a tooth 6 on its free end for embedding itself into the rear wall surface after the hanger is inserted in an appropriate hole 11 predrilled in the wall. A metallic ferrule 8 having wall-engaging teeth 10 is carried by the legs, and after insertion and proper orientation of the legs behind the wall, the body 7 is pivoted forwardly and the ferrule simultaneously pushed rearwardly, so that as the tooth 6 of each leg pierces the wall, the teeth 10 of the ferrule bite into the outer surface and thus the wall is sandwiched and gripped between the legs and the ferrule.
In the later Jones patent U.S. Pat. No. 2,789,783, a wire hanger includes a hook portion 10, an arcuate hole-engaging portion 11 and a parabolic-shaped body portion 14 terminating in a flattened drill 17 provided with a cutting tip 18. A hole 2 is cut through a wall using the cutting tip 18 and the body portion 14 is pushed through the hole until firmly seated therein. The cutting tip 18 is of greater diameter than the diameter of the rest of the hanger and thus the hole 2 has a greater diameter than the diameter of hole-engaging portion 11 and body portion 14. The arcuate hole-engaging portion 11 wedges in the hole, with mid-section of said portion 11 engaging the bottom interior portions of hole 2 and the end sections of said portion 11 engaging the upper interior portions of hole 2 near the interior and exterior surfaces of the wall. The cutting tip 18 bears against the wall inner surface and the hook portion extends forwardly from the outer surface of the wall for appropriate use.
Neither of the Wagner or Jones '783 patents, however, have proven entirely satisfactory. The Wagner hanger requires a pre-formed hole and thus its mounting requires the use of tools which may not be readily at hand. Furthermore, none of the weight placed on the hook 7 is supported by the hole, but instead is supported by the teeth 10 of ferrule 8 and to some extent by the teeth 6 of the legs 5. Another disadvantage is that an accidental upward force applied to the hook 7 can easily dislodge the teeth 6 from the interior surface of the wall by pivoting the arms 5 about ferrule 8. In the Jones '783 patent, the particular parabolic-shape of the body portion 14 does not permit penetration of the cutting tip 18 into the rear surface of the wall, but provides a tangential contact as shown in FIG. 1 of the patent. Thus, rotation of the hanger relative to the opening in the wall easily occurs and upward and downwardly sliding of the tip 18 on the interior wall surface occurs. Furthermore, where the body portion unitarily merges with the hole-engaging portion, the parabolic shape is continued. Thus, there is effectively point-to-point contact between the opening and the hole-engaging portion, and such contact occurs effectively at only three points. This results in a structure that is not locked in the wall and which allows movement and eventual enlargement of the hole 2 and breakout of the hanger. The Jones parabolic-shaped body portion, moreover,is limited to use with substantially a single size of wall thickness, and other wall thicknesses cannot be accommodated by the same hanger.
Smith U.S. Pat. No. 3,219,302 discloses several modifications of wall hangers, all which have in common a pointed end 17, a curved semicircular portion 16 which is very similar to a right angle bend, a vertical leg 15 connected to the semicircular portion by a bend that is more gradual than a right angle bend, a horizontal portion 12 connected to the vertical portion 15 in a right angle bend, and an exterior vertical leg portion 18 connected to the horizontal portion 12 by a right angle bend. In inserting the Smith hanger into a wall the pointed end 17 is pushed perpendicularly with a reciprocal twisting motion into the wall at the desired location. The point 17 forms a hole through the wall and when the point 17 reaches the interior side of the wall the semicircular portion 16 is eased through the hole. However, the near right angle shape of semicircular portion 16 causes enlargement of the hole made through the wall by the point 17 and, in addition, the right angle between the vertical portion 15 and the horizontal portion 12 further enlarges the hole in the wall. Furthermore, the semicircular portion 16 is free to slide up and down or sideways with the interior surface of the wall. It does not dig into the interior surface of the wall to result in tensioning those parts of the hanger extending between those points where it contacts the inner surface of the wall. While the patent speaks of a snap-in action, the undue enlargement of the hole formed by point 17 when the semicircular portion 16 and the right angle bend between horizontal and vertical portions 12 and 15 are forced through the hole contribute very little resistance to pivoting of the hanger and dislodgement from its position upon the application of an upward force to the threaded portion 19 or hook portion 14Y or 25 of the Smith hanger. Any spring bias provided by the interior portions of the Smith hanger tends to assist the pivoting of the horizontal portion 12 in the wall such that vertical portion 18 and semicircular portion 16 are urged away from the wall surface. This contributes to an unstable characteristic of the Smith hanger such that upward forces accidentally applied to the exterior portions of the hanger will cause pivoting of the hanger in the hole and over a period of time will result in such ultimate enlargement of the hole as to allow the hanger to fail. Since the semicircular portion 16 is free to move upward or downward on the interior surface of the wall, there is no spring bias created which would force the horizontal portion 12 against the lower portions of the hole in the wall or to counteract the effects of a weight acting on the hook portion. The Smith patent fails to disclose or suggest the invention disclosed and claimed herein.